Fire door for furnaces



May 6 1924.

J. G. ROEKNSON FIRE DOOR FOR FURNACES Filed April 1.1921 2 Sheets-Sheet l V Ir- Illllllllllllill l l Wantoz nected adjacent its outer end to the door 5 by means of a link 20 which is pivotally connected to both the lever 17 and to the door 5. The lever 18 is connected at one end to the door ring by means of the pivotal member 21 and is pivotally connected adjacent its opposite end to the door 6 by means of a link 22.

Fluid pressure connections 23 and 24, respeotively, are adapted to be controlled by a valve 25 which is movable by means of a pivoted foot lever 26. When the foot lever 26 is pressed downwardly the va ve member 25 is moved upwardly, thereby opening the pipe 23 so as to permit the fluid pressure from the source of supply to enter between the top of the cylinder 11 and the upper end of the piston 13. The space between the pistons 13 and 14 is always con nected with the source of supply of fluid pressure by means of the pipe 24'and the passage 27 to which said pipe is connected. When the pressure is introduced between the piston 13 and the top of the cylinder it will be apparent that the combined downward pressures on pistons 13 and 14 will be greater than the upward pressure on piston 13 and consequently this excess of downward pressure will force the pistons 13 and 14 downwardly in the cylinder, opening the doors 5 and 6. As the piston 13 moves downwardly the fluid which is between the pistons 13 and 14 will be reduced in volume owing to the difference in the diameters of the respective portions of the cylinder in which the said pistons operate. This decrease in volume results in increasing the pressure between the pistons, since a check valve of any ordinary construction is provided in the passage 24. The check valve while freely admitting fluid pressure through the passage 27 automatically prevents the flow of fluid in the opposite direction when the pressure in the cylinder exceeds the pressure in the source of fluid supply. Consequently as the piston 13 approaches the lower end of its respective portion of the cylinder 11, the pressure against the lower face of the piston increases until at a point adjacent the lower end of its stroke this pressure exactly counterbalances the pressure against the upper face of the piston 13. This method of operation results in the doors being brought to full open position and provides an air cushion which prevents any jar or destructive action upon the parts of the operating mechanism. When the foot lever 26 is released the operation is reversed, that is, the valve controlling the admission of fiuid pressure between the upper end of the cylinder and the top of the piston 13 is closed and an exhaust port is opened permitting the escape of this fluid pressure. The pressure upon the lower face of the piston 13,

no longer being counterbalanced by the pressure upon the upper face thereof, will move the piston 13 upwardly and bring the doors to closed position. Preferably there is an exhaust port leading from the upper portion of the cylinder 11 which is adapted to be closed or blinded by the piston 13 adjacent the end of its upward stroke, thus trapping a small volume of air between the piston 13 and the top of the cylinder. This entrapped air acts as a cushion to prevent the slamming of the doors with consequent damage to the latter and to their attachments and holds the doors in slightly spaced relation. There is, however, provided a bleed port (not shown) leading from this portion of the cylinder which slowly permits the escape of this entrapped air, thus permitting the upward pressure on the iston 13 to bring the doors into tightly closed position. The construction hereinabove described is shown and fully described in co-pending application, Serial No. 4358, filed J an. 25, 1915, and the descriptive matter is only inserted herein in order to accurately describe the operation of the construction shown. It will be observed that a downward movement of the piston rod 15 will force the lever 16 downwardly, and,

owing to the connection of the lever 16 with the levers 17 and 18, will cause the doors to be moved to open position, and likewise upward movement of the lever 16 will result in a closing movement of the doors 5 and 6. Inasmuch as the pressure from the source of supply is always admitted between the pistons 13 and 14 (except as hereinafter described) it will be obvious that the doors 5 and 6 will be held in closed position by a locking pressure which is measured by the difference in diameter or area of the pistons 13 and 14.

The passageway which leads from the source of fluid supply to the space between the pistons 13 and 14 is clearly illustrated in Fig. 4 and designated by the reference numeral 27. At a convenient point in this passage I provide a cylindrical opening 28 in which is seated a three-way stop cook 29. In normal position the passage 30 in the threeway stop cook or valve is in alinement with the corresponding ends of the passage 27 and permits the entrance of the fluid pressure to the space between the pistons 13 and 14. When, however, the threeway valve is given a quarter rotationin a clockwise direction the passage 27 is intercepted by a portion of the three-way valve and the passage 31 of the three-way valve is in alinement with the portion of the passage 27 leading to the cylinder 11, while the lower portion of the passage 30 isin alinement with a passage 32 which leads to the atmosphere. It will therefore be ob vious that when the valve 29 is turned as described the ompresses fluid betweenthe pistons 13' and 14*wi ll be released? and fur ther nfiialii' of fiiiid lietwefi these istons will be prevented until the cock 29 isagain rotated to its hhrma'ljpositi'oh;

Re'frrihgto Fig": 3', it' will be ob; served that I" provide OIi' tli'e door 5 adjac'eiit1tliepiv6tq7 thereof a bracket or lug 331 This Bracket" referably comprises a substantially rectangular ocket within which is" connected a lever" 34; Preferably the lever 34 pivhta'lly connected with the bracket or l'ug'ss by means of spin 35- which is adapted; to extend through an opening" 36 iii the said lever. In normal position of the parts illustrated in" Figs; r and 2; it will he observed that the upper end of the levj'eifi i isoverweighted so" as to cause the' same to lie of its own weight against slug 1 of the door" ling 1-. T0 permit the leverto be maintained this p'ds'i'tidn' iffSPebtiVe of the opening (if the" doorshy fluid pressure, I (iilfi away the upper portion of the wall sarr'y olea'raiicbetweii' the "wall-and the lever to prevent the overweight'edupper end of the later from beifig fo'reed away from the lug of the deer ring" duringtthe fluid pres sure-"operationof the? doors. It will beho'te'd that tl'iedever 34 is provided witli'ari-iiiclined portion 39 which extends over thepcint' of pivotal connection, that is; 35, of the leve'r, is further provided" with a handle" 40 which in normal position also overhangs the pivotal point of thelever and the contacting portion of the door ring 1, and that by constructing the lever in this manner it will always lie against the door ring when the doors are operated by fluid pressure.

The operation of the device is believed to be clear from the foregoing description. It might be pointed out, however, that when it is desired to partially open or crack the furnace doors it is only necessary to turn the valve 29 in a clockwise direction so as to release the fluid pressure between the pistons 13 and 14:. The lever 3% is then operated or pulled to the left until the desired opening between the fire doors is attained; the lever may then be released and if desired pushed over to a position in contact with the door ring '1. It will be obvious, however, that should the lever not have been turned to a position in contact with the door ring or lug after a cracking operation of the fire doors, the closing movement of the doors will automatically return the lever to its normal position. Owing to the balance between the doors 5 and 6 it will be seen that the doors will remain in any position to which the same have been moved by the lever 34 until it is the desire of the operator to close the same. To perform this closing operation the only step necessary is to give the stop cook or valve 29 a quarter rotation a c eater cishkwise direction sh as to bring th 'passag' -fidthereof into ali iie'nieiit with the adjacent ends or the passage ev,

wheres-peri the fluid pressure will be aid1i1it= ted E0 the space betwe'e the pistons 13' and 14,-and- 6w-ing tdthe' d iflerence in the respec'-' tive' diaiiietis'of these pistons the pressure;

willforce the piston 13 upwardly, causing the doors-5' an'd 6*to"be"" moved to" closed p0 sitioni I v Attention is directed to" the fact that by the" useof the" mechanism describedthe' firman of a locomotive is enabled to move the" doorsof-the fire boxfto open position and to close the same without moving from his seatat the left hand side of thecab. The principal pur ose- Oii providing cracking mechanism for locomotive" the doors is to cool (rows theboil'e'r by permitting Cold: air' is enter above the" are; thus reducing the steam pressure within the boiler'.- This step is" enerally employed when the locomotive or train is approaching terminals when the amount of steam required for" the train o eration is greatly reduced; It is at this time, however, thatis, whenthe' train is approaching" termina1s;thast the attentionof the fire man is required to observe signals and to confirm the engineer in the reading of the signals"controlling the-approach of the train. It is therefore imperative that the fireman be permitted-to operate the c'rackin'g me'cha ni'sm' without moving from his seat and without having his attention" distracted from his more-importantduty; By" using the mechanism hereinbefore described it is possible for the fireman to positively control the opening of the fire doors without moving from his position and for him to maintain 1 the doors in any desired position without interposing between the doors or any portion thereof a locking mechanism. c

Having now described my invention, what I claim and desire to secure by Letters Patent is v 1. In a device of the character described,

the combination with movable door mem-v open and closed positions, said means being adapted toexert a predetermined pressure upon sa1d door members when in closed pos1t1on, means for releasing sald pressure and means for manually opening said doors when the said pressure is released.

3. In adevice of the character described,

the combination with radially movable door members, of means operated by fluid pres sure and including a cylinder for moving said doors to open and closed positions, said means being adapted to exert pressure upon said doors to lock the same in closed posi tion, means carried by said cylinder for releasing the said locking pressure and manually operated lever means for moving said door members to an open position when said locking pressure is released.

d. In a device of the character described, the combination with arcuately movable door members, of means for moving the same to open and closed positions, said means including a cylinder and a plurality of spaced connected pistons, fluid pressure means for operating said pistons, saidcylinder having a passage to permit the fluid pressure to enter the space'between said pistons when said door members are in closed position, and means located in said passage for closing the same and for venting the space between said pistons to permit the manual operation of said door members.

5. In a device of the character described, the combination with arcuately 'mova-ble door members, of means operatedby fluid pressure and including a cylinder for normally moving said doors to open and closed positions, the said means being adapted to exert pressure upon said doors to lock the same in closed position, a valve carried by said cylinder for releasing the said locking pressure and manually operated lever means carried by one of said door members for moving said door members to an open position when said locking pressure is released. i

6. In a device of the character described, the combination with oppositely movable door members, of fluid pressure operated means for normally moving said door members to open and closed positions, said means being adapted to exert pressure against the opening movement of said doors when the latter are in closed position, a three-way valve adapted to be rotated to release said pressure, and a lever pivotally connected to one of said door members for facilitating the manual operation thereof to open position.

7 In a device of the character described, the combination with oppositely movable door members, of means for positively moving said doormembers to open and closed positions, said means including a cylinder and a plurality'of spaced connected pistons, fluid pressure means for operating said pis tons, said cylinder having a passage to permit the fluid pressure to enter the space between said pistons, and rotatable means located in said passage for controlling the admission of fluid pressure to said cylinder in termediate the said pistons, said means being adapted in one position to vent the space between the said pistons.

In testimony whereof I afiix my signature.

JAY G. ROBINSON. 

